Theoretically, pop (popular) culture is not a new or modern concept, it has long existed in human history in some form(s), right?

Of course.  Certain things" are popular at any given time in human culture (e.g. music, fashion, sports, technology).  What those "things" are, changes from day to day, week to week, month to month, year to year (meaning they are short-lived).  That's because people want their "thing" to be unique, and when others "get in on it", they quickly want to change to something "new".  Problem is that there is nothing "new".  It's existed before (in one form or another) - just not in the same lifetime.